Check-Trol is the solution for circulator installations. Installing a Check-Trol on the discharge of the circulator gives you the features of a Flow Control Valve, Isolation Valve and Companion Flange. Another advantage of the Check-Trol is the minimal pressure drop, especially when compared to the losses that can be experienced when a check valve is installed internal to the circulator. The Check-Trol flanges are packaged with an isolation flange of the same size to create a pair.